Rheostat



H. A" DOUGLAS.

RHEOSTAT.

APPLICATION FILED JUNE I, 1922.

1,438,753. 2 Patented Dec. 12,1922.

$27 1:9 024g as.

Patented Dec. 12, I922.

UNITED STATES HARRY A. DOUGLAS, BRONSON, MICHIGAN.

RHEOSTAT.

Application filed .Tune 1,

To all whom, it may concern:

Be it known that I, HARRY A. DOUGLAS, citizen of the United States, residin at Bronson, in the county of Branch and tate .of Michigan, have invented a cer-tainfnew and useful Improvement in Rheostats, of which the following is a full, clear, concise,- and exact description.

My invention relates to electrical apparatus employing a spirally coiled wire winding and a contacting wiper engaging the wire of'such winding for varying the ampere turns thereof. The device of my invention is useful in connection with rheostats having spiral windings or in connection with any other electrical apparatus having spiral windings.

In accordance with one of the characteristics of my invention the wiper is disposed within the hollow of the winding and has a threaded mounting of a pitch equal to that of the pitch Of the spiral winding so that the contacting end of thearm will fol-- low the wire as the arm is turned to change the amount of wire that is tov be included in circuit.

In accordance with another characteristic of the invention one of the elements of the mounting for the wiper has circumscribing marks thereon that are distributed along the same and a plurality of longitudinal marks which are distributed around the same. I

I will explain my invention more fully by reference to the accompanying drawing in which Fig. l is an axial sectional view illustrating the preferred embodiment thereof; Fig. 2 is a view on line 22 of F ig. 3 on a larger scale; Fig. 3 is a sectional view on line 3-3 of F ig. 1, parts being broken away; Fig. 4.- is a view in elevation,

partially in section, of a modification; and Fig. 5 is a plan view of a part of the structure as it appears in Fig. 4;.

Like parts are indicated by similar characters of reference throughout the different figures."

The wirei of the rheostat or other wound electrical instrument is spirally disposed upon the interior of a hollow drum 2 in the construction of Figs. 1, 2 and 3, or upon the exterior of such drum, as indicated in Figs. 4 and a. This drum is cup-shaped and is mounted upon any suitable support 3 by means of the attaching screws 4. A threaded sleeve 5 is cc-axial with the drum 1922. Serial No. 565,155.

and extends through the bottom thereof and partially into the sleeve continuation 6 of the cup. A threaded shaft 7 is in threaded engagement with the sleeve and carries a contacting wiper 8. This contacting wiper, in the form of the invention shown in Figs. 1,' 2 and 3, is within the drum and, in the form shown in Figs. 4 and 5, is upon the exterior of the drum. In either case the contacting end of the wiper is arcuate in form to correspond incross section to the cross section of the wire engaged thereby.

The threading at the shaft and sleeve and the spiral of the coiled wire 1 are of the same pitch in either construction so that the contacting end of the wiper will follow the wire engaged thereby as the shaft 7 is turned. The outer end of the shaft is provided with a plurality of equally spaced apart circumscribing marks 9 thereon which are distributed along the same and a plurality of longitudinal marks 10 thereon that are distributed around the same. There is a stationary marker 11 upon the sleeve 6 operating in conjunction with the marks 9 and 10 to enable the notation of the adjustment efi'ected.

My invention is of particular service in connection with radio systems of communication as will be apparent to those skilled in the art, though the invention is not to be limited to any use to which it may be put.

, I use the term pitch in its common acceptation, meaning the amount of advance of a single screw thread in one turn expressed in lineal distance along or parallel to the screw axis, irrespective of the angularity of the thread to the screw axis.

While I have herein shown and partlcularly described the preferred embodiment of my invention I do not wish to be limited to the precise details of construction shown as changes may readily be made without departing from the spirit of my inventlon, but having thus described my invention, I claim as new and desire to secure by Letters Patent the following 1. The combination with a spirally coiled wire winding; of a contacting wiper engaging the wire of the winding; a mounting for the wiper including a sleeve and a shaft that .carries the wiper and is 1n threaded engagement with said sleeve through whose bore said shaft passes, the

threading at the shaft and sleeve and the spiral of the coiled Wire being of the same pitch, the outer end of said shaft projecting beyond said sleeve and having circumscribing marks thereon distributed along the shaft and a plurality of longitudinal marks distributed around the shaft, there being a marker adjacent the aforesaid marks.

2. The combination with, a spirally coiled wire winding; of a contacting Wiper engaging the wire of the winding; a mounting for the Wiper including one element in the form of a sleeve and a second element in the form of a shaft that is in threaded engagement with the sleeve and which projects through the bore thereof, one of these elements carrying said wiper, the threading at the shaft and sleeve and the spiral of the coiled wire being of the same pitch, the projecting end of the shaft having circumscribing marks thereon distributed along the shaft and a plurality of longitudinal marks dis tributed around the shaft, there being a marker adjacent the aforesaid marks.

3. The combination with a spirally coiled wire winding; of a contacting Wiper engaging the Wire of the winding; a mounting for the Wiper including one element in the form of a sleeve and a second element in the form of a shaft that is in threaded engagement with the sleeve, one of these elements carrying said wiper, the threading of the shaft and sleeve and the spiral of the coiled Wire being of the same pitch, one of these elements having circumscribing marks thereon distributed along the same and a piurality of longitudinal marks distributed around the same, there being a marker adjacent the aforesaid marks. 7

4:. The combination with a spirally coiled wire winding; of a contacting wiper engaging the'wire of the winding; a mountin for the Wiper including a sleeve and a shaft that carries the Wiper and is in threaded engagement-,with said sleeve through whose bore said shaft passes, the threading at the shaftand sleeve and the spiral of the coiled wire being of the same pitch, the outer end of said shaft projecting beyond said sleeve and having circumscribing marks thereon distributed along the shaft and a plurality of longitudinal marks distributed around the shaft.

5. The combination with a spirally coiled wire winding; of a contacting wiper engaging the wire of the winding; a mountingfor the wiper including one element in the form of a sleeve and a second element-in the form. of a shaft that is in threaded engagement with the sleeve and which projec'ts through the bore thereof, one of these elements carrying said wiper, the threading at the shaft and sleeve and the spiral of the coiled Wire being of the same pitch, the projecting end of the shaft having circumscribing marks thereon distributed along the shaft and a plurality of longitudinal marks distributed around the shaft. I

6. The combination with a spirally coiled wire winding; of a contacting wiper engaging the Wire of the winding; a mounting for the wiper including one element in the form of a sleeve and a second element in the form of a shaft that is in threaded engagement with the sleeve, one of these elements car- 7 rying said-wiper, the threading of the shaft and sleeve and the spiral of the coiled wire being of the same pitch, one of these elements having circumscribing marks thereon distributed along the same and a plurality of. longitudinal marks distributed around the same.

7. The combination with a hollow spirally coiled wire winding; of a contacting wiper within the Winding and engaging the Wire thereof; and amounting for the wiper including one element in the form of a sleeve and a second element in the form of a shaft that is in threaded engagement with the sleeve, one of these elements carrying said wiper, the threading at the shaft and sleeve and the spirally coiled wire being of the same pitch.

8. The combination with a spirally coiled wire winding; of a contact wiper engaging the wire of the Winding; a mounting for the wiper including two elements in threaded engagement, one carrying the wiper, the threading of these elements and the spiral of the coiled wire being of the same pitch.

9. The combination with a spirally coiled wire winding; of a contact wiper engaging the wire of the Winding; a mounting or one of these members including two elements in threaded engagement, one carrying this member, the threading of these elements and the spiral of the coiled wire being of the same pitch. a

In witness whereof, I hereunto subscribe I my name this 26th day of Ma A. D., 1922.

. HARRY A. OUGLAS. 

